首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   427篇
  免费   9篇
  国内免费   7篇
安全科学   30篇
废物处理   6篇
环保管理   87篇
综合类   33篇
基础理论   132篇
污染及防治   107篇
评价与监测   26篇
社会与环境   17篇
灾害及防治   5篇
  2022年   5篇
  2021年   3篇
  2020年   3篇
  2019年   10篇
  2018年   4篇
  2017年   9篇
  2016年   12篇
  2015年   21篇
  2014年   14篇
  2013年   35篇
  2012年   17篇
  2011年   21篇
  2010年   20篇
  2009年   16篇
  2008年   26篇
  2007年   32篇
  2006年   15篇
  2005年   11篇
  2004年   17篇
  2003年   18篇
  2002年   5篇
  2001年   15篇
  2000年   13篇
  1999年   9篇
  1998年   8篇
  1997年   7篇
  1996年   4篇
  1995年   6篇
  1994年   5篇
  1993年   11篇
  1992年   2篇
  1991年   2篇
  1990年   4篇
  1989年   4篇
  1988年   4篇
  1987年   3篇
  1984年   3篇
  1983年   4篇
  1982年   5篇
  1980年   3篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   2篇
  1974年   2篇
  1973年   1篇
  1972年   1篇
  1971年   4篇
  1970年   2篇
  1968年   1篇
排序方式: 共有443条查询结果,搜索用时 562 毫秒
91.
The provision of green and open space in the face of wider development pressure is a key urban challenge. Despite this, few studies have critically investigated the quality of life implications of such provision. This paper focuses on perceptions of built environment factors and their influence on neighbourhood quality of life. Data are drawn from a household survey questionnaire completed by 483 residents living in three neighbourhoods in Dublin, Ireland – an inner city neighbourhood, a suburb and a peri-urban settlement. Positive perceptions of green and open space were identified as important predictors of high levels of neighbourhood satisfaction, surpassed only by dwelling characteristics. This suggests that development strategies which fail to provide for properly planned green and open spaces may be detrimental to neighbourhood quality of life. Furthermore, the results suggest a need for design solutions which consider neighbourhood typology in achieving improved neighbourhood quality of life.  相似文献   
92.
The geographic variation of silver concentrations in the black turban snail, Tegula funebralis, along the California coastline indicates an anthropogenic influence. Relatively elevated levels of the metal occur in organisms adjacent to major wastewater outfalls compared to those from less populated areas. This parallels the distributions of silver concentrations in other molluscs within the area. It, therefore, substantiates the proposal that the pattern is primarily due to external factors, such as wastewater discharges, rather than intraspecific differences among the samples.  相似文献   
93.
The American Academy of Pediatrics recommends that women breastfeed because of improved health outcomes for mothers and children. Because maternal employment during the first year of the child's life has been identified as a reason for breastfeeding cessation, we develop and test a role‐theory‐based framework to explain women's continuation of breastfeeding after return to work (Study 1) and report results of an exploratory study linking breastfeeding at work with job attitudes and well‐being (Study 2). Applying survival analysis to a longitudinal dataset gathered by the Centers for Disease Control (Study 1), we identify pregnant women's perceived employer support for breastfeeding as a predictor of women's breastfeeding goal intentions. Supervisors' negative workplace remarks about breastfeeding related to an eightfold increase of women's likelihood to discontinue exclusive breastfeeding and perceived support for breastfeeding after return to work predicted exclusive breastfeeding continuation. Results of Study 2 suggest that women who return to work and continue breastfeeding experience more family‐to‐work conflict and overload than women who do not reconcile work and breastfeeding. Further, results of Study 2 provide preliminary evidence suggesting that perceptions of supervisor and coworker support for breastfeeding relate positively to general perceptions of organizational support and negatively to depressive symptoms. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
94.
Abstract

Penicillic acid and ochratoxin A are environmentally important toxic fungal metabolites (mycotoxins) that are synergistic in combination. The effects of penicillic acid on the pancreatic enzyme, :arboxypeptidase A were investigated in vitro and in vivo. A broad range of inhibition in vitro of the enzyme by PA was demonstrated with a half‐maximal inhibitory concentration equal to 1.1 x 10‐4M PA. Inhibition of carboxypeptidase A was time and temperature dependent, and resulted in decreased conversion of parent ochratoxin A to the non‐toxic metabolite, ochratoxin alpha. Studies in vivo demonstrated a penicillic acid‐dependent inhibition of pancreatic carboxypeptidase A activity in the mouse and the chicken following multiple oral exposure. It is postulated that the mode of toxic interaction of the two mycotoxins may be due, in part, to impaired detoxification of ochratoxin A through peni‐cillic acid depletion of carboxypeptidase A activity.  相似文献   
95.
A detailed sensitivity analysis was conducted to quantify the contributions of various emission sources to ozone (O3), fine particulate matter (PM2.5), and regional haze in the Southeastern United States. O3 and particulate matter (PM) levels were estimated using the Community Multiscale Air Quality (CMAQ) modeling system and light extinction values were calculated from modeled PM concentrations. First, the base case was established using the emission projections for the year 2009. Then, in each model run, SO2, primary carbon (PC), NH3, NOx or VOC emissions from a particular source category in a certain geographic area were reduced by 30% and the responses were determined by calculating the difference between the results of the reduced emission case and the base case.The sensitivity of summertime O3 to VOC emissions is small in the Southeast and ground-level NOx controls are generally more beneficial than elevated NOx controls (per unit mass of emissions reduced). SO2 emission reduction is the most beneficial control strategy in reducing summertime PM2.5 levels and improving visibility in the Southeast and electric generating utilities are the single largest source of SO2. Controlling PC emissions can be very effective locally, especially in winter. Reducing NH3 emissions is an effective strategy to reduce wintertime ammonium nitrate (NO3NH4) levels and improve visibility; NOx emissions reductions are not as effective. The results presented here will help the development of specific emission control strategies for future attainment of the National Ambient Air Quality Standards in the region.  相似文献   
96.
Numerical simulations of the evolution of the planetary boundary layer (PBL) and nocturnal low-level jets (LLJ) have been carried out using MM5 (version 3.3) with four-dimensional data assimilation (FDDA) for a high pollution episode in the northeastern United States during July 15–20, 1999. In this paper, we assess the impact of different parameterizations on the PBL evolution with two schemes: the Blackadar PBL, a hybrid local (stable regime) and non-local (convective regime) mixing scheme; and the Gayno–Seaman PBL, a turbulent kinetic energy (TKE)-based eddy diffusion scheme. No FDDA was applied within the PBL to evaluate the ability of the two schemes to reproduce the PBL structure and its temporal variation. The restriction of the application of FDDA to the atmosphere above the PBL or the lowest 8 model levels, whichever is higher, has significantly improved the predicted strength and timing of the LLJ during the night. A systematic analysis of the PBL evolution has been performed for the primary meteorological fields (temperature, specific humidity, horizontal winds) and for the derived parameters such as the PBL height, virtual potential temperature, relative humidity, and cloud cover fraction. There are substantial differences between the PBL structures and evolutions simulated by these two different schemes. The model results were compared with independent observations (that were not used in FDDA) measured by aircraft, RASS and wind profiler, lidar, and tethered balloon platforms during the summer of 1999 as part of the NorthEast Oxidant and Particle Study (NE-OPS). The observations tend to support the non-local mixing mechanism better than the layer-to-layer eddy diffusion in the convective PBL.  相似文献   
97.
Ecosystem Impacts of Geoengineering: A Review for Developing a Science Plan   总被引:1,自引:0,他引:1  
Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO(2)) removal (CDR), which removes CO(2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research.  相似文献   
98.
Dewatered municipal biosolids (DMBs) were applied to a field at a rate of ~22 Mg dw ha(-1) in October 2008. Pharmaceuticals and personal care products (PPCPs) were monitored in groundwater, tile drainage, soil, DMB aggregates incorporated into the soil post-land application, and in the grain of wheat grown on the field for a period of ~1 year following application. Over 80 PPCPs were analyzed in the source DMB. PPCPs selected for in-depth monitoring included: antibiotics (tetracyclines, fluoroquinolones), bacteriocides (triclosan, triclocarban), beta-blockers (atenolol, propranolol, metaprolol), antidepressants (fluoxetine, citalopram, venlafaxine, sertraline), antifungals (miconazole), analgesics (acetaminophen, ibuprofen) and anticonvulsants (carbamazepine). PPCPs in tile were observed twice, ~3 weeks and 2 months post-application. Of all PPCPs measured in tile drainage, only carbamazepine, ibuprofen, acetaminophen, triclosan, triclocarban, venlafaxine, and citalopram were detected (5-74 ng L(-1)). PPCPs were not detected in groundwater >2 m depth below the soil surface, and concentrations above detection limits at 2 m depth were only observed once just after the first rain event post-application. In groundwater, all compounds found in tile, except carbamazepine, acetaminophen and citalopram, were detected (10-19 ng L(-1)). PPCPs were detected in DMB aggregates incorporated in soil up to 1 year post-application, with miconazole and fluoxetine having the lowest percent reductions over 1 year (~50%). For several compounds in these aggregates, concentration declines were of exponential decay form. No PPCPs were detected in the grain of wheat planted post-application on the field. No PPCPs were ever detected in water, soil or grain samples from the reference plot, where no DMB was applied.  相似文献   
99.
Short chain chlorinated paraffins (SCCPs) are a group of persistent organic pollutants (POPs) of increasing concern, but are to date not widely investigated in the environment, largely due to the challenges involved in their quantification. Here, SCCPs were quantified in marine sediments from the Firth of Clyde, Scotland, by gas chromatography with electron capture negative ionisation mass spectrometry (GC-ECNIMS) and through carbon skeleton analysis by gas chromatography with flame ionisation detection (GC-FID), and the analytical challenges encountered are discussed. Concentrations in the sediments ranged from 0.4 to 69 μg kg−1 when determined by GC-ECNIMS, and from 5.6 to 379 μg kg−1 when determined by GC-FID. For 8 out of 11 samples, analysis by GC-FID gave higher results than analysis by GC-ECNIMS. Unexpected aspects of the analysis, such as the presence of high concentrations of longer chain chlorinated paraffins in the samples, are also presented.  相似文献   
100.
I am delighted to have this opportunity to address the members attending this 67th annual meeting of the Air Pollution Control Association. Before I came here this morning, I glanced through the pamphlet describing the scheduled technical programs. I was struck by the range and sophistication of the technical sessions that are scheduled for the next three days. Your program makes it very clear that a national program of air quality management requires a large dose of scientific inquiry and engineering know-how. You are the experts who have the training, experience and commitment necessary to provide strong professional leadership in the battle to achieve and maintain clean air for the American people.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号